The invention is based on an electromechanical brake application device, particularly for a rail vehicle brake.
Currently, three types of wheel braking systems are essentially used in the rail vehicle field: Pneumatic or electro-pneumatic braking systems, hydraulic or electro-hydraulic braking systems as well as mechanical or electromechanical braking systems. The wheel braking system may be constructed as an active or passive braking system, depending on whether the power of the brake actuator has to be applied for the engaging (active braking system) or for the releasing of the brake (passive braking system). In case of operating disturbances, energy is stored in air brake reservoirs if pneumatic systems are used; energy is stored in hydraulic reservoirs if hydraulic systems are used; and energy is accumulated in the form of accumulator-type springs when electromechanical systems are used.
From the prior art, electromechanical brake application devices are known which have a service-type brake unit as well as an accumulator-type brake unit which has an energy accumulator. The service-type brake unit contains a braking power generator for the application and/or release of the brake; for example, in the form of an electric-motor drive which can be controlled by a control device for slip-controlled or load-corrected braking. The accumulator-type brake unit comprises at least one energy accumulator for the storage and supply of energy for the application of the brake as a service-type emergency brake during a safety braking demand; as a parking brake; or a safety braking level, in the event of a failure of the service-type brake unit.
A power converter provides a conversion of the energy supplied by the braking power generator and/or by the energy accumulator to a brake application movement and comprises, for example, a brake spindle driven by the electric-motor drive.
For activating the energy accumulator, a locking device is provided which can be unlocked upon a safety braking and/or parking braking demand signal. The accumulator-type brake unit is generally constructed as a spring brake, the accumulator-type spring being held in the tensioned condition by the locking device. Upon the safety braking demand signal, which is controlled, for example, by a safety loop of the rail vehicle into the locking device, the locking device is released and the power of the accumulator-type spring can be transmitted by the power converter to brake shoes.
However, it is a disadvantage that, while the brake application device is intact, no non-skid-controlled or load-corrected feeding of the braking power can be achieved in order to permit a certain braking comfort during safety and parking braking.
In view of the above, the present invention is based on further developing an electromechanical brake application device such that, also during a safety braking and/or parking braking, a braking can take place in a non-skid-controlled and/or load-corrected manner.
When the safety braking or parking braking is demanded, while the brake application device is intact, a braking can take place in complete comfort, that is, in a load-corrected and or slip—or non-skid-controlled manner, by the service-type brake unit. The controlling-in of the braking power is monitored by the control and monitoring device. When the controlling-in of the braking power is correct (brake application device is intact), this control and monitoring device prevents the opening of the locking device and thus, in the event of a safety braking, the brake slip of the wheels of the rail vehicles which is frequently observed when the accumulator-type brake unit is triggered. As a result of this measure, the driving comfort can be improved, and the mechanical loads and the wear of the brake system can be reduced.
As a result of additional measures, advantageous further developments and improvements of the electro-mechanical brake application device can be achieved.
According to a particularly preferable measure, in the case of an intact brake application device, a feeding of the safety braking and/or parking braking signal to the locking device can be prevented by a switching device. The switching device can be controlled by the control and monitoring device, and instead a signal for maintaining the locked condition can be controlled in.
The locking device preferably has an electromagnetically operable construction, can be locked when energized and can be unlocked when not energized. The safety braking demand signal is formed by a currentless condition which can be controlled in by a safety loop of the rail vehicle.
The switching device contains at least one relay which, upon the safety braking demand signal and when the brake application device is intact, connects the locking device with a voltage source. An unlocking of the accumulator-type brake unit will then be reliably prevented by means of simple devices.
As an alternative, the locking device may have several locking elements, of which at least one locking element is sufficient for keeping the locking device locked. Thus, when the brake application device is intact, the control and monitoring device can output to this at least one locking element the signal for keeping the locking device locked.
The locking device may be electromagnetically operable and contains several solenoid coils as the locking elements for generating magnetic forces which lock or unlock the locking device. The magnetic force of at least one solenoid coil controllable by the control and monitoring device is sufficient for keeping the locking device locked. When the locking device is constructed with a double or multiple coil, a separate control of the individual coils can be implemented in mutually separated electric circuits, for example, by the control and monitoring device, on the one hand, and by a safety loop of the rail vehicle, on the other hand. Solenoid coils are identical parts; one or two additional solenoid coil(s) take up only a little more space. For this reason, the described solution requires little space and can be implemented in a cost-effective manner. Furthermore, solenoid coils are unsusceptible with respect to shock loads or vibration loads and have a long service life.
These and other aspects of the present invention will become apparent from the following detailed description of the invention, when considered in conjunction with accompanying drawings.